DESCRIPTION (Adapted from the Applicant's Description): The purpose of the proposed research is to understand the role of maternal emotion in parenting during social interaction with an infant. This goal will be realized by a systematic investigation of the associations of mothers experience, expression, and regulation of negative emotions with the quality of mother- infant interaction. Three different theoretical models will be tested, in which maternal emotion regulation is conceptualized as a main, a moderating, and a mediating factor, respectively, in linking maternal emotional experience and expressivity to the quality of mother-infant interaction. Moreover, an optimal model of emotion regulation is proposed, which suggests that there is a curvilinear relation between emotion regulation and the quality of mother- infant interaction. The proposed study will build on the existing research on emotion and emotion regulation as well as parenting behaviors in infancy using maternal self- reports and behavioral observation to achieve the following three objectives: 1) to investigate individual differences in mothers experience and expression of negative emotions and their associations with the quality of mother-infant interaction; 2) to examine the role of emotion regulation in linking maternal experience and expression of negative emotions with the quality of mother- infant interaction; and 3) to understand the role of infant characteristics in the relations of maternal experience, expression, and regulation of negative emotions to the quality of mother-infant interaction.